Photonic devices comprising a semiconductor are widely used in modern telecommunication systems. Typically the light is transmitted in optical fibers. Therefore, the light has to be coupled from a first photonic device into an optical fiber. After transmitting the light in the optical fiber the light has to be coupled back to a second photonic device. Therefore, coupling light from and to an optical fiber is an important aspect in the telecommunication field.
US 2013/0181233 A1 discloses a silicon photonics wafer that includes an active silicon photonics layer, a thin buried oxide layer, and a silicon substrate is received. The thin buried oxide layer is located between the active silicon photonics layer and the silicon substrate. An electrical CMOS wafer that includes an active electrical layer is also received. The active silicon photonics layer of the silicon photonics wafer is flip chip bonded to the active electrical layer of the electrical CMOS wafer. The silicon substrate is removed exposing a backside surface of the thin buried oxide layer. A low-optical refractive index backing wafer is added to the exposed backside surface of the thin buried oxide layer. The low-optical refractive index backing wafer is a glass substrate or silicon substrate wafer. The silicon substrate wafer includes a thick oxide layer that is attached to the thin buried oxide layer.